1. Field of the Invention
The present invention relates to a differential, and more particularly, to a position compensating differential locking mechanism.
2. Discussion of Related Art
Differential gear mechanisms, simply referred to as differentials, are well known devices frequently used in the drive trains of most vehicles. The differential is usually connected between an input driving shaft {typically a drive shaft from the vehicle engine} and a pair of output driven shafts (typically a pair of axle shafts connected to the vehicle wheels). The differential distributes torque from the input shaft equally to the two output shafts, while permitting such output shafts to rotate at different speeds under certain conditions. As a result, torque is supplied to both wheels of the vehicle as it negotiates a turn, while permitting the outside wheel to turn faster than the inside wheel.
In a conventional open differential, the movements of the various internal components of the differential are not restricted in any significant fashion. Thus, the differential functions in the desirable manner described above under most circumstances. However, when one of the wheels loses traction with the ground, due to, for example, wet or icy surfaces, the differential will reduce the amount of torque supplied to the other wheel. Consequently, the vehicle can become immobilized.
To prevent immobilization, some differentials are provided with a locking mechanism. When actuated, the locking mechanism restricts the movement of some of the differential""s internal components. This restriction allows the drive shaft to provide torque to both wheels instead of providing torque only to the wheel with less traction. Some differential locks remain locked and automatically unlock while turning corners. Other differentials use a driver-initiated control to manually engage and disengage the lock at the driver""s command.
One conventional differential locking mechanism includes a first set of teeth on a differential case of the differential and a clutch collar having a second set of teeth configured to selectively engage the first set of teeth. The clutch collar is supported on a drive axle shaft extending through the differential case. The mechanism further includes a yoke supported on a pivot shaft and received within a groove in the clutch collar. A lever is also supported on the pivot shaft and is disposed outside of the differential housing where it may be coupled to a spring-loaded cable system manually operated by the vehicle operator. This conventional differential has several disadvantages. First, the locking mechanism can only be engaged while the vehicle is at rest. Second, the manual engagement of the locking mechanism requires a physical effort on the part of the operator. Third, the locking mechanism requires a relatively large amount of space to link the lever and the cable system.
The inventors herein have recognized a need for a differential that will minimize and/or eliminate one or more of the above-identified deficiencies.
The present invention provides a differential with a position compensating differential locking mechanism.
A differential in accordance with one embodiment of the present invention includes a differential case having a first set of teeth and defining a central bore. A drive axle shaft is disposed within the central bore and is rotatable therein. The differential also includes a clutch collar mounted on the drive axle shaft. The clutch collar has a second set of teeth configured to selectively engage the first set of teeth and to prevent relative rotation between the drive axle shaft and the differential case. The clutch collar further defines a groove. A yoke is supported on a pivot shaft and is received within the groove in the clutch collar. The differential further includes a lever supported on the pivot shaft and a first spring disposed between the yoke and the lever. An actuator selectively urges the lever and the yoke in a first rotational direction to a first position. A second spring urges the lever and the yoke in a second rotational direction to a second position. The first and second sets of teeth are urged into engagement in one of the first and the second positions and the first and the second sets of teeth are urged to disengage in another of the first and the second positions.
A differential in accordance with the present invention has one or more advantages as compared to the prior art. First, the differential can operate freely during vehicle travel regardless of the level of engagement between the opposed clutch members. Second, the inventive differential may eliminate the need for manual operation of the differential locking mechanism. Third, the locking mechanism of the inventive differential is compact thereby conserving vehicle space.
This and other features and objects of this invention will become apparent to one skilled in the art from the following detailed description and the accompanying drawings illustrating features of this invention by way of example.